1. Technical Field
The present invention relates to a transport apparatus which transports a medium, and an image reading apparatus which generates image data by reading an image from the medium transported by the transport apparatus.
2. Related Art
In JP-A-2010-217542, an example of a printing apparatus which performs printing on a transported medium is disclosed. A transport apparatus of the printing apparatus is provided with a pick-up roller, a separation roller pair, a resist roller pair, a feeding roller pair, and a discharge roller pair which are disposed in order from an upstream side to a downstream side in a transport direction of the medium.
In addition, as such a transport apparatus, an apparatus which is provided with a first motor and a second motor as power sources is known. In such an apparatus, the first motor functions as a power source of the pick-up roller and the separation roller pair, and the second motor functions as a power source of the resist roller pair, the feeding roller pair, and the discharge roller pair.
However, in the above-described transport apparatus, when the medium is nipped by the resist roller pair and the feeding roller pair in the middle of being transported, there is a case where driving of the first motor is stopped, even when the medium is still in a state of being nipped by the separation roller pair. In this case, an operation of the separation roller pair is stopped, and the medium is transported to the downstream side in the transport direction by only the power from the second motor. When the driving of the first motor is stopped in this manner, there is a case where back tension increases, a load applied to the resist roller pair rapidly increases, and the transport speed of the medium by the operation of the resist roller pair changes.
In addition, in a case where the rotation of the separation roller pair is stopped in this manner, when a rear end of the medium passes through the separation roller pair, and the medium nipped by the separation roller pair is released, the back tension decreases, and the load applied to the resist roller pair rapidly decreases. Even in this case, there is a case where the transport speed of the medium by the operation of the resist roller pair changes.
In addition, while performing the printing on the medium by a printing portion, if the transport speed of the medium changes, the printing quality deteriorates.
In addition, when specifying the above-described transport apparatus as a transport apparatus of an image reading apparatus, the following problems are generated. In other words, in such an image reading apparatus, while a reading portion reads an image recorded on the medium, there is a case where the transport speed of the medium changes due to the change in the back tension as described above. In this case, distortion is generated in the image read by the reading portion due to the change in the transport speed of the medium, and the accuracy of generated image data deteriorates.